1. Field of the Invention
The present invention relates to computers. More specifically, the invention relates to devices and methods for controlling power allocation to expansion slots in a computer system having hot-plug capability.
2. Description of the Related Art
Computer systems are an integral part of the day-to-day operations of most businesses. Often such systems are tailored for use by a particular business through the addition of various peripheral devices and other computer systems via communication buses. The peripheral devices are generally connected to the communication buses by an adapter card coupled to an expansion or card slot. These peripheral devices have often been the cause of data corruption and/or system down-time. This resulted in the insertion and removal of the adapter cards associated with the failed peripheral devices, which historically, has required powering down the computer system.
This often results in loss of productive work by staff.
To facilitate adapter card manipulation while reducing computer system down-time, a xe2x80x9cHot-Plugxe2x80x9d specification has been adopted which sets forth devices and structures to allow adapter card manipulation without terminating power to the computer system. One such specification is a PCI (Peripheral Component Interconnect) Hot-Plug specification which sets standards for aspects of removal and insertion of PCI adapter cards while the system is running. The Hot-Plug specification is applicable to a variety of computer systems and is typically implemented in server-based systems. It defines a sequence of user actions and system management facilities that inform the operating system of an intention to insert of remove an adapter card.
Adapter cards are not generally designed to be connected to a slot that is already powered. Accordingly, the Hot-Plug specification defines a sequence of user actions and system behavior to ensure the removal of power to a slot before adapter card manipulation.
The insertion of an adapter card, however, poses a risk to both a user and computer system during power allocation. The user may unintentionally contact power traces or pins on the adapter card if power is allocated thereto at an arbitrary time. This poses a risk of harm to the user, as well as a risk that the computer system may be damaged.
What is needed, therefore, is a device and method that prevents allocation of power to a card slot until the risk of exposing a user to the biasing power has abated.
A computer system and a method for allocating power to hot-plugged adapter cards placed in a card slot that features delaying the power allocation until a user is clear of the adapter card. In this manner, risk of harm to the user, as well as a risk that the computer system may be damaged, is greatly reduced. To that end, the computer system includes a processor, a card slot in data communication with the processor, a memory in data communication with the processor, and a power supply in electrical communication with the processor. The card slot is in one of two operational states associated with it. In one state, an adapter card is disposed in the card slot, defining a connected state. In the remaining state, an adapter card is not present in the card slot, defining an unconnected state. The memory stores computer-readable data that includes code to be operated on by the processor to allocate power to the card slot upon both a detection of a change of state of the card slot and the occurrence of a predefined system event. The predefined system event is typically a system interrupt that is generated by an activation of a switch.
In a first embodiment, the switch comprises the computer system""s power button. Upon sensing that one or more card slots have changed states, first interrupt, such as a System Management Interrupt (SMI) is generated that is sensed by the processor. The processor then executes a subroutine that reconfigures the power button to generate a second SMI upon activation of the power button. Upon sensing the second SMI the processor allocates power to the card slots that changed states. After allocation of power, additional signals received from the power button would be interpreted to power-down or power-up the computer system. Were the power button to include a light emitting element, such as a light emitting diode (LED), the processor would also execute a subroutine, after receiving the first SMI, to cause the LED to periodically flash or vary intensity. In this manner, a physically perceivable stimulus is generated. The stimulus would alert a user that the computer system is ready to allocate power to an adapter card that had just been hot-plugged into a card slot. Alternatively, an audible or other physical stimulus could be provided to the user, indicating that the computer system is ready to allocate power to the aforementioned card slot.
In another embodiment, the switch is one of a plurality of switches associated with the individual keys of a keyboard. As with the power button, upon one or more card slots changing states, an interrupt, such as an SMI is generated that is sensed by the processor. The processor executes a subroutine that interprets the signals received from the keyboard. Were the signals to correspond to a predetermined sequence of keys, the memory would then invoke a subroutine that would allocate power to the card slots that changed states.
In a third embodiment, the switch is connected between a moveable panel and a frame of a chassis of the computer system. The chassis houses the card slot, the memory and the power supply. The moveable panel has two positions, breached and secured. The switch has one of two modes, each of which is uniquely associated with one of the two positions. The system event occurs when the switch is in the mode associated with the moveable panel being in the secured position.
These and other embodiment of the present invention, along with many of its advantages and features, are described in more detail below and are shown in the attached drawings.